Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/5799

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  • Master Thesis
    Tasarlanmış Mikroorganizmalar ile Katma Değeri Yüksek Karotenoidlerin Biyosentezi
    (Abdullah Gül Üniversitesi, Fen Bilimleri Enstitüsü, 2024) Arslansoy, Nuriye; Fidan, Özkan
    Carotenoids are pigment molecules that play an important role in coloring plants, algae, and other organisms. These molecules exhibit various biological activities such as anticancer, antiviral and antioxidant activities. They have a huge market size and are mainly used in the food, feed, and cosmetic industries. The current supply chain for carotenoids is mostly relied on the extraction from plants and/or chemical synthesis for certain carotenoids. However, these strategies have various bottlenecks and disadvantages such as being affected by climate change, more difficult and costly extraction processes, and environmental issues. These can be overcome with microbial biosynthesis, which not only addresses the previous problems but also provides advantages of producing in a short time and scale-up for industrial production. In this research, we aimed to biosynthesize the high value-added carotenoids by engineered microorganisms. The genome of a native producer of zeaxanthin diglucoside, identified as endophytic Pseudomonas sp. 102515, was first edited by CRISPR-Cas9 to knock out zeaxanthin glucosyltransferase (CrtX), lycopene β-cyclase (CrtY) and beta-carotene hydroxylase (CrtZ). This led to ΔcrtX, ΔcrtY and ΔcrtZ mutant strains of Pseudomonas sp. 102515. On the other hand, overexpression plasmids carrying crtW, CaZEP and CaZEP-CaCCSm40 genes were constructed and transformed to ΔcrtX mutant to synthesize astaxanthin, violaxanthin and capsanthin/capsorubin. HPLC analysis of extracts from mutant strains and overexpression strains revealed that all the engineered strains produced the corresponding carotenoids such as zeaxanthin, β-carotene, and lycopene. Thus, this study paved the way for the biosynthesis of valuable carotenoids in the engineered endophytic bacteria.
  • Master Thesis
    Escherichia Coli Konak Organizmada GLP-1 Analoğunun Rekombinant Üretimi
    (Abdullah Gül Üniversitesi, Fen Bilimleri Enstitüsü, 2024) Çalış, Burak; Fidan, Özkan
    Diabetes is the most serious metabolic disorder correlated with obesity, hypertension and cardiovascular conditions. High prevalence of Type II Diabetes Mellitus (T2DM) indicates the need for new medication development. In developing therapeutics, higher efficiency and fewer adverse effect features are targeted primarily. Recombinant protein-based biotechnological drug molecules have been developed and used for the treatment of T2DM. Especially, GLP-1 analogues are known by their self-limiting mechanism and insulinotropic effect. In this study, a novel GLP-1 analogue with increased stability and efficiency is produced using recombinant E. coli. The expression plasmid was constructed and confirmed by restriction digestion and whole plasmid sequencing. Then, itwas transformed into various E. coli strains followed by optimized lysis, growth and expression conditions to maximize the yield of the GLP-1 analogue. Various parameters such as pre-induction time, induction point, induction IPTG concentration and post-induction temperature were tested for the succesfull expression with maximum yield. Consequently, it was achieved that E. coli BL21(DE3) as strain, 0.2 mM IPTG induction at OD600nm of 0.6 and 18 °C overnight post-induction growth was the most promising conditions. Under these conditions, the GLP-1 analogue was obtained in the insoluble fraction. Following protein analysis and purification, quantification was performed and the highest titer of GLP-1 analogue was measured as 626 µg/ml. As future prospect, using another host organism and changing growth conditions can provide obtaining target protein in the soluble form. Keywords: T2DM, GLP-1 analogue, recombinant DNA technology, protein expression, E. coli